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2011 Now Shows Fourth Largest Basin Runoff In 41 Years; Big Meltdown Has 6-8 More Weeks
Posted on Friday, June 10, 2011 (PST)

During a wet and cool April and May – a time when the Columbia River basin’s water stores usually begin to drain – estimated runoff volumes were boosted by more than 23 million acre feet of water, according to Bonneville Power Administration officials.

 

Peter Cogswell, Steve Oliver and Rick Pendergrass on Tuesday briefed the Northwest Power and Conservation Council on the current status of the Federal Columbia River Power System and how its dams are being operated to meet power generation, salmon protection, flood control and other demands in what is one of the highest runoff seasons in many years.

 

Low elevation meltdown has fueled high flows in recent weeks. But mid and high elevation snowpacks across the Columbia-Snake river continued building well into the spring season and now hold in excess of 150 to 175 percent of average moisture content.

 

“We expect that to come off here in the next six to eight weeks,” Pendergrass said.

 

“It is a very unusual occurrence” for the basin to experience such a period of sustained high flows, Oliver said. Flows past Vancouver, Wash., on the lower Columbia have been at or above the 16-foot minimum flood stage for the past two weeks. The entire system is being managed to hold to 500,000 cubic feet per second or less at Bonneville Dam, which is located about 40 miles upstream of the Portland-Vancouver metropolitan area. Flows have been at that level since May 24.

 

Flows have been nearly as high as in 1997 when the highest runoff on record flowed down from the Snake and upper Columbia River.

 

The Northwest River Forecast Center’s June 7 “final” water supply forecast is for a runoff volume from April through September of 134 million acre feet past The Dalles Dam on the lower Columbia. That would be 136 percent of normal and the fourth largest volume on the 41-year record. The highest volume was 140.9 MAF in 1997, followed by 139.7 MAF in 1974 and 134.8 MAF in 1972.

 

The wet spring resulted in The Dalles forecast being boosted considerably. The April 7 final forecast was for 107 MAF, which would have been 108 percent of the 30-year average runoff during the April-September period.

 

The Snake River basin is particularly laden. The new NWRFC forecast predicts 37.3 MAF will flush down from the upper Snake and past Lower Granite dam in southeast Washington. That would be 155 percent of average for the April-September period. Lower Granite is the fourth dam upstream from the Snake’s confluence with the Columbia.

 

The reservoir backed up by Dworshak Dam in west-central Idaho is expected to receive 142 percent of its average inflows. Dworshak is on the North Fork of the Clearwater, which feeds into the Clearwater and then the Snake upstream of Lower Granite.

 

Grand Coulee Dam inflows are predicted to total 80.4 MAF this year, which would be 126 percent of average.

 

The high flows so far have forced dam operators to spill even more water than is required under a court order to provide an passage for juvenile salmon and steelhead headed for the ocean.

 

Bonneville has since May 18 been forced to implement its new “environmental redispatch policy” for parts of all but two days. The policy calls on non-hydro energy flowing into the transmission grid, including fossil-fuel and other thermal generation and wind energy, to be partially and temporarily limited so that hydro production can be maximized during low power demand periods. Running more water through the turbines reduces the volume that has to be spilled. Spill stirs up “total dissolved gas,” which can be harmful to fish.

 

Through Tuesday a total of 59,313 megawatt hours of energy had been displaced with “graveyard shift” timeframes as a result of the redispatches, Pendergrass said.

 

With an uptick this week in Snake River runoff, much of the responsibility for holding down flows past Bonneville Dam has been shifted to the mid-Columbia’s Grand Coulee Dam in central Washington.

 

Grand Coulee had been in a flood control mode, discharging as much water as possible in order to reserve space for the looming meltdown. Since May 28 the Bureau had been sending down more than 260 kcfs as a daily average, which came close to matching daily inflows.

 

Since Wednesday outflows have dropped to 203 kcfs, with the spilled amount cut nearly in half. The result has been an increase of the reservoir level of more than two feet per day. At the end of the day Thursday Lake Roosevelt, Grand Coulee’s reservoir, had risen to 1,242.3 feet elevation. Full pool is 1,290. The reservoir had been as low as 1,220, which is “12 feet from empty,” Pendergrass said.

 

Following the spill reduction, TDG measurements below Grand Coulee dropped below 140 percent for the first time since May 27. The measurement was 134.6 percent on average Thursday. State water quality regulations allow levels of up to 120 percent in dams’ tailwaters, but during extreme higher flows it can become impossible to hold TDG down. The gas caps are intended to protect fish and other aquatic species that might be harmed by higher TDG levels.

 

On the Snake, inflows to Lower Granite’s reservoir have increased from 155 kcfs a week ago to 207 kcfs Thursday as a daily average. The run-of-the-river project is passing a like amount of water, having boosted spill levels in recent days.

 

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* Summer Chinook Run Expected To Be Best Since 1980, Fishing Starts June 16; Summer Steelhead Moving

 

With Bonneville Dam fish counts holding strong, sport and commercial fishers are preparing to shift after June 15 from a “spring” chinook emphasis to targeting what is expected to be the highest “summer” chinook salmon return to the Columbia River basin since at least 1980.

 

The Columbia River Compact on Thursday approved the first summer commercial treaty gill-net fisheries starting June 16 (2.5 days) and June 20 (3.5 days) in Zone 6’s reservoirs above Bonneville, The Dalles and John Day dams. Tribal fishermen can catch and sell salmon, steelhead, shad, yellow perch, bass, walleye, catfish and carp. The Oregon-Washington Compact also OK’d sales of fish caught by tribal fishers by hook and line from specific sites below Bonneville Dam during the June 16-July 31 period.

 

The Compact, which met Tuesday via telephone conference line and Thursday in Rainier, Wash., also set eight-hour non-tribal commercial salmon fisheries that begin at 9 p.m. on June 16 and June 22 in Zones 1-5 from below Bonneville down to the mouth of the Columbia. The Compact is comprised of representatives of the directors of the Oregon and Washington departments of fish and wildlife.

 

Meanwhile, Nez Perce, Warm Springs, Umatilla and Yakama tribal fishers continue to sell spring chinook and other fishes caught by hook and line from riverside platforms above and below Bonneville, which is located at about river mile 146. The Compact on Tuesday approved an expansion of the below Bonneville platform, hook and line tribal commercial fishery from three days per week to daily through June 15.

 

For fishery management purposes, chinook salmon spawners passing over Bonneville are considered “upriver” spring chinook through June 15. From June 16 through July 31, chinook counted as they climb over Bonneville’s fish ladders are considered summer chinook.

 

Upriver Snake River and upper Columbia spring chinook are stocks bound for hatcheries and tributary spawning grounds upstream of Bonneville in Idaho, Oregon and Washington. Summer chinook are fish destined for areas above the mid Columbia’s central Washington’s Priest Rapids Dam, though the run includes some Snake River summer chinook.

 

Naturally produced upriver Snake and upper Columbia spring chinook are protected under the Endangered Species Act, as are wild upriver summer steelhead. Steelhead counts at Bonneville are beginning to mount at Bonneville as summer chinook counts wax and spring chinook counts wane.

 

Based in large part on dam counts and lower river harvest data, the Technical Advisory Committee on Wednesday upgraded the upriver spring chinook run-size estimate from 204,000 to 214,000 adult returns to the mouth of the Columbia.

 

Already, through Wednesday, 185,125 adult spring chinook had been counted passing over Bonneville, and state staff estimate that anglers and the non-Indian commercial fleet will have taken (harvest and post-release mortality) an estimated 13,400 upriver fish. The tribes estimate they have caught 2,300 upriver spring chinook this year below Bonneville.

 

The Bonneville count is already second best in the past seven years. The upriver spring chinook count last year was 277,389 through June 15. Daily counts have averaged about 2,500 over the past five days.

 

The treaty tribes expect to catch about 8.7 percent of their 9.1 percent allocation of the upriver spring chinook run and non-treaty fisheries, commercial and recreational, are expected to haul in about 1.5 percent of the upriver run as compared to their 1.9 percent allocation. A state-tribal management agreement limits harvest on upriver spring chinook in order to protect the wild portion of the run. Non-tribal fishers are required to release unmarked fish unharmed. A large majority of the hatchery-produced fish are marked with a clipped adipose fin.

 

The preseason forecast is for a return of 91,000 adult Upper Columbia summer chinook, a stock that is not ESA listed. Fishery managers estimate that daily counts at Bonneville will average 3,100 summer chinook June 16-30 before tapering off to about 700 by the end of July.

 

Summer steelhead are also starting to return from the ocean. A total of 3,985 had passed Bonneville through Wednesday with daily counts approaching 100. The preseason forecast is for a return of 390,900 upriver summer steelhead past Bonneville, which would be 95 percent of the 10-year average of 410,100. Lower river summer steelhead returns have averaged 77,800 over the past 10 years.

 

Sockeye salmon are also beginning to make their run towards upriver spawning sites. The count at Bonneville Wednesday was 88 to bring the 2011 total to 238. Fisheries officials predict that 161,900 adult sockeye will return to the mouth of the Columbia on their way toward central Washington’s Wenatchee (33,000) and Okanogan (126,000) river basins and to central Idaho’s Stanley basin (2,100). Last year’s sockeye return was a whopping 387,900, which was the largest on a record dating back to 1980. The recent 10-year average is 126,000.

 

Fisheries are managed to hold non-Indian impacts on listed wild Snake River sockeye to 1 percent or less. Treaty impacts are capped at 7 percent.

 

Summer chinook recreational fisheries are scheduled to be open from the Astoria, Ore.,-Megler Bridge upstream to Priest Rapids Dam in central Washington from June 16 through July 31. The fisheries will be mark-selective for summer chinook, allowing the retention of adipose fin-clipped hatchery fish only. The Columbia mainstem spring chinook sport fishery officially ends June 15.

 

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The Columbia Basin Bulletin, Bend, Oregon. For information or comments call 541-312-8860.
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